The most common type of apparatus for cats is the litter box, sometimes referred to simply as a cat box. This type of receptacle usually contains a loose material, such as sand or sawdust which functions as an absorbent while still making it possible for the cat to bury his waste conveniently.
Litter boxes of this type work fairly well over the short term but, after several days of waste-buildup the absorbent material usually becomes saturated with excrement and emits a very unpleasant odor.
To overcome this problem some litter material is treated with a deodorizing substance so as to mask the otherwise offensive odor. In principle, this would seem to be a satisfactory solution to the problem; however, in practice, the effect is usually disappointing. This is due to the fact that the cat waste comes into direct contact with the deodorant and negates its deodorizing effect.
The reaction which occurs between the deodorant and waste material is not fully understood and no effort is made here to explain it; nevertheless, it is a known fact that deodorants which are added directly to absorbent litter generally have a very short effective life and for all practical purposes, they are ineffective in curing the waste-odor problem.